Enable mythconfirmation dialog to pause playback

Description

First patch (Enable-mythconfirmation-dialog-to-pause-playback.patch) enhances the behavior of the MythConfirmationDialog? during playback: If a MythUserMessage? with ExtraData? set to "pauseplayback" (instead of a timeout) is received while in playback, playback is paused until the dialog is dissmissed.

The second patch (add-network-control-command-message_pause.patch) adds the network control command "message_pause" which uses the feature introduce in the first patch. I'm not really happy with the command name, but i did not want to change the syntax of "message" because i think this would break a lot of peoples scripts...

Both patches were created against the master branch.

Since i don't know what's the preferred way to submit patches here are the patches as commits on github: